Prior methods for repairing damaged portions of pipelines include moving a liner tube impregnated with a liquid material capable of curing and hardening to a position within the pipe where the damaged portion is located. The liner tube is installed by pulling, pushing, or everting the liner into the host pipe. Once the liner is positioned within the host pipe, it is pressurized, usually by an inflation bladder, causing the liner to press against the interior wall of the host pipe, and the liner is cured by applying heat, such as steam or hot water. These liners can also be cured at ambient temperatures by chemical mixtures that generate an exothermic reaction, the use of ultraviolet light or other photo curing initiators, or by electron beam curing. The liner tube forms an interior liner in the pipe for the pipeline being repaired. One such process is known as cured-in-place pipelining.
In most pipelines, lateral or branch pipes are connected to main pipes. In sewer systems, the connection of a lateral pipe to a main sewer pipe is accomplished by forming a hole in the main line with a hammer. The lateral pipe is then simply abutted against the hole, and then the juncture is covered with mortar, dirt, or the like. Damage or leaking can occur at the junction between the lateral pipe and the main pipe, which is generally known as one of the weakest points in a collection sewer system. T-shaped or Y-shaped liner tubes have been utilized to fit within the junction between the lateral and main pipes. Liner tubes form a T-shaped or Y-shaped liner after hardening to the interior of the junction between the pipes. Again, inflation bladders are typically used to pressurize the liners against the interior walls of the host pipes.
The repair assembly may include a scrim-reinforced bladder assembly including an inflatable main bladder that is sized close (≦10%) to the inner diameter of the pipe without stretching the bladder, and a lateral bladder that is inserted into a lateral pipe. The main and lateral bladders may be fluidly connected, or they may each have their own air supply conduit. The scrim, which provides reinforcement to the bladder, also limits stretch and prevents the bladder from bursting under pressure. For example, a bladder for a 24-inch pipeline would measure approximately from 21-inch to 24-inch in diameter. The bladder is positioned over a launcher, which can have an outside diameter of approximately 12 inches and where each end of the bladder is gathered to fit around the 12-inch launcher tube and secured by banding like that of a hose clamp. However, the size results in folds along the circumference of the bladder.
The folds can create problems. The main bladder, having a diameter twice that of the launcher, can rotate, even when rubber bands have been used to restrict the rotation of the main bladder. Furthermore, the launcher and bladder are combined with a main and lateral resin absorbent lining, and the assembly is robotically positioned in the main pipe where the lateral lining is aligned with the lateral pipe. As air pressure is applied to the main bladder, the bladder begins to inflate and the folded sections of the bladder contact the main liner and the pipe in sporadic locations around the interior circumference of the main lining and the main pipe. This can result in the liner assembly moving or rotating such that the lateral lining is no longer in alignment with the lateral pipe.
In addition, the main bladder can contact the inner pipe wall for a distance nearly equal to the distance between the bandings at the ends of the launcher. In order for the reinforced bladder to achieve this pipe surface contact, the main bladder must be longer than the distance between the banding measures. This is done so as to provide a mainline bladder having a length that is equal to the distance between the bandings, while accounting for the distance from the exterior surface of the launcher to the interior surface of the pipe. For example, if the distance between the bands is 34 inches, and the distance from outer surface of the launcher to the inner surface of the pipe is 6-inches at each end, the repair would require a bladder having a length of approximately 46-inches. This is not accounting for the amount of bladder at the bandings.
However, the excess bladder material allows the bladder to slide or move along the length of the launcher in either direction as the launcher and liner assembly are positioned in the pipe. The liner may contact the pipe walls, and the liner can shift on the bladder, and/or the bladder can shift on the launcher. For example, some pipes have slight bending or offset joints, which typically do not prevent the lining equipment and materials from passing through the pipe, but which could cause the liner to become out of communication with the bladder, and likewise the bladder out of communication with the launcher.
Furthermore, the positioning of the assembly can be accomplished by using a self-propelled robot having an attachable and detachable connecting device for connecting the robot to a launcher and a camera that displays video of the robot's work to technicians who control the robot from outside of the pipe. The launcher can be outfitted with a flexible spring or a laser that is in perfect alignment (12:00 clock reference) of the lateral liner. In this example, the distance from the spring or laser (or a similar device) to the first side of the lateral liner can be 23-inches, which is a measurement the technician will use for robotic positioning. The method involves moving the robot and connected launcher through the pipe until the spring, laser, or the like is aligned with the center of the lateral pipe. The launcher can then be moved so the spring or laser makes contact at the first side of the lateral pipe, and then the launcher can be moved 23 inches so the lateral liner is aligned with the lateral pipe.
The method works so long as the main bladder does not move substantially relative to the launcher, and the liner does not move substantially relative to the bladder. Any rotation of the launcher can affect the accuracy of the pipe repair. The longitudinal movement is also an issue as the launcher and liner are moved through the pipe. Any longitudinal movement of the bladder can slide can affect the technician who uses 23 inches for his or her measurement. The problem can also arise when a sealing gasket is used, as the gasket may also slide or otherwise move such that the lateral liner and the gasket are no longer in communication.
There is therefore, a need in the art for a method and means for lining a pipe that mitigates the likelihood that a liner and/or bladder assembly will move prior to repairing the pipe and after alignment.